Kanika Kanjanachatree, Kanoktorn Piyathamrongrut, and Piyapong Kaewteen

pp. 87 - 97

Abstract

Nucleation in the spherical pearl production from Akoya pearl oysters Pinctada fucata (Gould, 1850) obtained low survival rate, and the nuclei were frequently excluded. Using relaxants before nucleation could lower the oysters' metabolism, so that nucleation might be improved. This experiment showed that
appropriate concentrations of propylene phenoxetol, 30% magnesium sulfate and 10% MS 222 were 2.5, 15 and 2 ml/l treated for 6, 11 and 7 minutes, respectively. At the beginning of anesthetization the oysters had
high oxygen consumption, but after that decreased continuously until constant, while those without the relaxant treatment had higher oxygen consumption. Oysters reared in the sea as soon as the nucleation was finished, had higher rate of survival after 8 months than those which rested in cement tanks for 4 weeks before rearing in the sea, and also the bead rejection decreased. However, pearl formation of the oysters without relaxant treatment was significantly better than of those with the treatments: the average pearl diameter obtained from the former was 6.62 mm. while those from the latter were 6.52, 6.48 and 6.46 mm. when treated with 30% magnesium sulfate, propylene phenoxetol and 10% MS 222, respectively.